/Engine/Plugins/Runtime/RigVM/Source/RigVMDeveloper/Public/RigVMModel/RigVMPin.h
Returns the top-most parent Pin, so for example for "Node.Transform.Translation.X" this returns the Pin for "Node.Transform".
[UFUNCTION](Programming/UnrealArchitecture/Reference/Functions)(BlueprintCallable, Category=RigVMPin) [URigVMPin](API\Plugins\RigVMDeveloper\RigVMModel\URigVMPin) * GetRootPin() const